通过低电离层调制加热能够产生极低频/甚低频(ELF/VLF)波.基于调制加热理论,并引入相控阵天线思想,建立了通过双波束幅度调制模式(DAM)和圆形几何调制模式(CGM)产生ELF/VLF波的定向辐射模型,并通过与实验数据的对比验证了模型的正确性.据此模型,采用HARRP加热阵参数,对比分析了上述两种定向辐射模式与常规幅度调制模式(AM)之间的特性差异,并研究了调制频率(fELF/VLF)和加热波束与垂直方向倾角(ψ)对各模式的影响.结果表明:相对AM模式,通过合理设置初始相位、f ELF/VLF和ψ,DAM模式和CGM模式在实现ELF/VLF信号定向辐射的同时还可以提高其辐射强度,相对AM模式,CGM模式信号强度最大提高约11.3 dB. Very low frequency / very low frequency (ELF / VLF) waves can be generated by low ionospheric modulation heating.According to the theory of modulation heating and the idea of ​​phased array antenna, a new method is proposed that uses dual-beam amplitude modulation (DAM) and circular geometry modulation (CGM), a directional radiation model of ELF / VLF wave was generated and compared with the experimental data to verify the correctness of the model.According to the model, the parameter of HARRP heating array was used to compare the two directional radiation patterns with conventional amplitude modulation (AMF), and the effect of modulation frequency (fELF / VLF) and vertical tilt angle (ψ) on the modes was studied.The results show that in the relative AM mode, by setting the initial phase rationably, f ELF / VLF and ψ, DAM mode and CGM mode can enhance the radiation intensity while achieving the directional radiation of ELF / VLF signal. Compared with AM mode, the signal strength of CGM mode can be improved by about 11.3 dB.